Tokkai Hei 5-129029 published by the Japanese Patent Office in 1993 and Tokkai Hei 7-302609 published by the Japanese Patent Office in 1995 disclose a fuel cell power plant provided with a hydrogen recirculation passage. A reformate gas processed by the reformer is transformed into a hydrogen-rich gas as a result of permeating a membrane hydrogen separator and thereafter is supplied to an anode chamber of a fuel cell stack.
The anode effluent from the anode chamber is recirculated to the post-separation side of the membrane hydrogen separator through a hydrogen recirculation passage and is mixed with the hydrogen-rich gas which has permeated through the membrane hydrogen separator. Thereafter this gas is re-supplied to the anode chamber.